Seat

ABSTRACT

A seat, in particular a motor-vehicle seat, having a seat-adjusting mechanism is described. The seat-adjusting mechanism comprises a motor-driven spindle unit with a nut which has an inner profiled portion and a spindle which has an outer profiled portion. The spindle unit comprises a plurality of rollers which are arranged in planetary manner between the nut and the spindle and cooperate with the nut and the spindle. Each of the rollers has at least one outer profiled portion.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The invention relates to a seat, in particular a motor-vehicle seat, having a seat-adjusting mechanism comprising a motor-driven spindle unit, the spindle unit having a nut which has an inner profiled portion and a spindle which has an outer profiled portion.

[0003] 2. Discussion of the Prior Art

[0004] Seat-adjusting mechanisms are known which have a motor, a reducing gear and a spindle unit for converting a rotary movement into an axial movement. The spindle unit of such a seat-adjusting mechanism comprises a nut having an inner profiled portion and a spindle which is arranged inside the nut and cooperates with the nut. The spindle is provided with an outer profiled portion which is in engagement with the inner profiled portion of the nut.

[0005] The known seat-adjusting mechanisms have numerous disadvantages, including undesired jamming of the spindle unit against the end stops of the seat-adjusting mechanisms. Furthermore, the adjusting noises of seat-adjusting mechanisms of this type, which may be attributed amongst other things to the friction within the spindle unit, are irritating. It has moreover been shown that the known seat-adjusting mechanisms are highly sensitive to dirt.

[0006] The object of the invention is to provide a seat having an improved seat-adjusting mechanism which is in particular less susceptible to faults.

SUMMARY OF THE INVENTION

[0007] In the case of a seat of the type described above, this object is achieved in that the spindle unit of the seat-adjusting mechanism comprises a plurality of rollers which are arranged in planetary manner between the nut and the spindle and cooperate with the nut and the spindle, and which each have at least one outer profiled portion for example in the form of a thread or grooves.

[0008] As a result of constructing the spindle unit in this manner, it is possible to prevent jamming against the end positions of the seat-adjusting mechanism, especially in the case of seats having motor-driven seat-adjusting mechanisms. Moreover, the friction loss for a spindle unit of this type is exceptionally low, so that the adjusting noises made by the seat-adjusting mechanism are also less pronounced.

[0009] According to a first embodiment of the invention, the rollers are each provided with a single outer profiled portion. By way of this outer profiled portion, each of the rollers is in engagement with the inner profiled portion of the nut and also in engagement with the outer profiled portion of the spindle. There are various possibilities available for the concrete realization of the particular engagement. Thus, for example, grooves can be brought into engagement with grooves, grooves can be brought into engagement with a thread, or a thread can be brought into engagement with a thread.

[0010] According to a further embodiment of the invention, the rollers each have two different outer profiled portions, each of the rollers being in engagement with the inner profiled portion of the nut by means of a first outer profiled portion, and being in engagement with the outer profiled portion of the spindle by means of a second outer profiled portion. There are a plurality of possibilities available for the concrete realization of the cooperation between the rollers and the nut, and the rollers and the spindle. Thus, for example, grooves can be brought into engagement with grooves, grooves can be brought into engagement with a thread, or a thread can be brought into engagement with a thread.

[0011] In the case of rollers which have two different outer profiled portions, the two outer profiled portions can be arranged in those regions of each roller which follow one another in the axial direction. Thus, with respect to the axial extent of a roller, regions of the first outer profiled portion can alternate with regions of the second outer profiled portion. The axial extent of each of these regions and the number of individual grooves or thread pitches in each of these regions can be adapted according to the concrete requirements.

[0012] The first outer profiled portion of each roller, which cooperates with the nut, is preferably coarser than the second outer profiled portion which cooperates with the spindle. It is particularly preferable for the second outer profiled portion to be a fine profiled portion, for example a fine thread or fine grooves.

[0013] As a result of providing a small thread pitch for the outer profiled portion of the rollers, which cooperates with the spindle, or for the outer profiled portion of the spindle, it is possible to achieve a large reduction ratio and consequently also a large axial force. The drive power necessary for the spindle unit, and thus also the overall weight of the seat-adjusting mechanism, can therefore be significantly reduced.

[0014] Each roller advantageously has one or more outer profiled portions in the form of grooves. In practice, such a construction of the rollers has proven particularly expedient in preventing the seat-adjusting mechanism from jamming in its end positions.

[0015] The grooves of rollers which are adjacent in the peripheral direction of the spindle can be offset axially with respect to one another. This measure ensures that all rollers which are arranged in planetary manner about the spindle engage precisely in the thread of the spindle. The amount of axial offset is selected in dependence on the thread pitch.

[0016] The inner profiled portion of the nut can be of a grooved construction. In this case, the outer profiled portion of the rollers, which cooperates with the inner profiled portion of the nut, is also preferably of a grooved construction.

[0017] The individual components of the spindle unit, in particular the spindle itself, can have a profiled portion both in the form of a single-lead and a multi-lead thread. Here, the pitch of the thread of the spindle is advantageously less than 5 mm and particularly advantageously less than 1 mm. To achieve a large reduction ratio, it is also possible to select even smaller pitches of for example less than 0.3 mm.

[0018] The number of rollers can be freely selected. However, it is preferable for a minimum of three rollers and a maximum of 6 rollers to be provided. If the spindle has an outer profiled portion or the nut has an inner profiled portion in the form of a multi-lead thread, the number of rollers can correspond to the number of threads. Advantageously, a minimum of three and a maximum of six threads are provided.

[0019] According to a preferred embodiment of the invention, the efficiency of the spindle unit is greater than 50%. To measure the efficiency, the spindle unit moves a mass vertically upwards. The efficiency is then calculated as a quotient from the product of this mass, the gravitational acceleration and the lifting speed, and from the product of the motor torque and the angular velocity of the motor.

[0020] It is also possible for the spindle unit to be restored from the end positions of the seat-adjusting mechanism. If the spindle unit is acted on by an axial force, this is then converted into a rotary movement. As a result, jamming of the spindle unit is prevented to the greatest possible extent. If a restorable spindle unit is used, the seat-adjusting mechanism preferably has a blocking mechanism to prevent unintentional adjustment of the seat.

[0021] In addition to a drive motor and a spindle unit, the seat-adjusting mechanism can also have a reducing gear. However, according to a preferred embodiment, the seat-adjusting mechanism is constructed without gears. A gearless seat-adjusting mechanism is not only exceptionally low in weight, but also has smaller spatial dimensions. It is advantageous to realize a gearless seat-adjusting mechanism by using a spindle unit comprising a plurality of planetary rollers, since a spindle unit of this type has a low friction loss and a high efficiency. In addition, as a result of the low friction loss, it is also possible for the spindle unit itself to have a high reduction ratio.

[0022] The seat-adjusting mechanism can be incorporated for example in a seat under-frame such that the spindle of the spindle unit is mounted stationary with respect to the seat under-frame and the nut is movable relative to the seat under-frame. In this case, the seat-adjusting mechanism can comprise an actuating lever, which has a lever arm coupled to the nut.

[0023] According to a preferred embodiment of the invention, the seat-adjusting mechanism comprises a unit for determining the axial position or the angular position of the spindle. A unit of this type enables the absolute or relative position of the spindle to be determined, and therefore enables a return to a previous or initial position of the seat-adjusting mechanism. A separate unit for determining the axial or the angular position of the spindle is then particularly expedient if the slip of the spindle unit is no longer negligible, since in this case the number of revolutions of the motor can no longer be used as a measure of the path covered by the spindle. By means of a separate unit for determining the position or the angular position of the spindle, a memory function for the seat can also be realized in the case of a spindle unit which is liable to slip, in order to enable for example-automatic actuation of a plurality of pre-programmed seat adjustments.

[0024] The unit for determining for example the position of the spindle can be constructed as a conventional displacement sensor. The displacement sensor can comprise a potentiometer or be constructed as an optical system. A further possibility for realizing the displacement sensor consists in moving the spindle against, for example, a spring having a linear spring constant, and then determining the position of the spindle by measuring the force which his necessary to compress the spring.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Preferred constructions and further advantages of the invention are revealed in the exemplary embodiments and in the Figures, in which:

[0026]FIGS. 1A, 1B show a first exemplary embodiment of a spindle unit;

[0027]FIG. 2 shows a second embodiment of a spindle unit;

[0028]FIG. 3 shows a vehicle seat with different adjustment possibilities;

[0029]FIG. 4 shows part of a seat-adjusting mechanism; and

[0030]FIG. 5 shows a seat under-frame with the assembled seat-adjusting mechanism.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0031]FIGS. 1A and 1B show a first exemplary embodiment of a spindle unit 10 suitable for incorporation into a seat according to the invention. FIG. 1A shows an axial section through the spindle unit 10 and FIG. 1B shows a section along the line IB-IB in FIG. 1A. A spindle unit of this type is disclosed for example in EP 0 320 621 B1 herewith incorporated by reference. In the case of a seat according to the invention, it is possible to provide a spindle unit having all the features disclosed in EP 0 320 621 B1.

[0032] The spindle unit 10 illustrated in FIGS. 1A and 1B comprises a spindle 12 having an outer thread 14 and a hollow cylindrical nut 16 which surrounds the outside of the spindle 12 radially and has a plurality of coarse V-shaped grooves 18. Six rollers 20 are arranged in planetary manner between the spindle 12 and the nut 16. Each of the rollers 20 has two different, radially outer profiled portions in the form of a first grooved profile 22 and a second grooved profile 24. With respect to the axial extent of each roller 20, the two grooved profiles 22, 24 are constructed in alternating regions of each roller 20. The relatively coarse grooved profile 24 is in engagement with the corresponding grooved profile 18 of the nut 16, and the comparatively fine grooved profile 24 is in engagement with the fine thread 14 of the spindle 12.

[0033] The fine grooves of the individual rollers 20 surrounding the spindle 12 are constructed such that a first axially directed groove of a roller 20 is in each case offset somewhat axially with respect to a corresponding groove of a roller 20 which is adjacent in the peripheral direction of the spindle 12. This ensures that the fine grooves 24 of each roller 20 engage precisely in the fine thread 14 of the spindle 12.

[0034] An alternative construction (which is not illustrated in FIGS. 1A and 1B) of the spindle unit 10 provides for the fine thread 14 of the spindle 12 to be replaced by fine grooves and for a fine thread to be provided instead of the fine grooves 24 of the rollers 20.

[0035]FIG. 2 shows a second exemplary embodiment of a spindle unit 10 for a seat according to the invention. The spindle unit 10 illustrated in FIG. 2 corresponds substantially to the spindle unit 10 illustrated in FIGS. 1A and 1B and is disclosed for example in DE 27 18 888 C2 herewith incorporated by reference. The seat according to the invention can comprise a spindle unit 10 having all the features disclosed in DE 27 18 888 C2.

[0036] Like the spindle unit 10 according to FIGS. 1A and 1B, the spindle unit 10 according to FIG. 2 has a nut 16, a spindle 12 and a total of six rollers 20 arranged in planetary manner between the nut 16 and the spindle 12. Of these six rollers 20, only four rollers 20 are illustrated in FIG. 2.

[0037] Unlike the rollers 20 of the spindle unit 10 according to FIGS. 1A and 1B, the rollers 20 of the spindle unit 10 according to FIG. 2 have only a single profiled portion in the form of grooves 22. By way of these grooves 22, the rollers 20 are in engagement with corresponding grooves 18 of the nut 16 and also in engagement with a corresponding thread 14 of the spindle 12. The pitch of the thread 14 of the spindle 12 is typically 0.5 to 5 mm. The thread 14 of the spindle 12 is a six-lead thread. Accordingly, six rollers 20 are provided.

[0038] In the case of the spindle unit 10 according to FIG. 2, the nut 16 has an inner profiled portion in the form of grooves 18. Deviating from this, the inner profiled portion of the nut 16 can, however, also be constructed as thread having for example six leads.

[0039]FIG. 3 shows a motor-vehicle seat 30 according to the invention. The seat 30 comprises a seat under-frame 32, a seat surface 34 and a backrest 36. Three separate seat-adjusting mechanisms enable vertical adjustment 38 of the seat surface 34, longitudinal adjustment 40 of the seat 30 and angle adjustment 42 of the backrest 36.

[0040] By way of example, FIG. 4 shows one of the three seat-adjusting mechanisms 50 used in the case of the seat 30 according to FIG. 3. The seat-adjusting mechanism 50 comprises a motor 52, a reducing gear 54 coupled to the motor 52, and a spindle unit 10 coupled to the reducing gear 54. The spindle unit 10, which can be constructed for example in the manner illustrated in FIGS. 1A and 1B or in the manner illustrated in FIG. 2, comprises a spindle 12, a nut 16 and planetary rollers which are not illustrated.

[0041] The spindle 12 is coupled to the reducing gear 54 and the nut 16 is securely connected to a rail 56 having a U-shaped cross-section. With the aid of the spindle unit 10, a rotary movement of the spindle 12 is converted into an axial movement of the rail 56.

[0042] In the case of the seat-adjusting mechanism 50 which is illustrated in FIG. 4 and comprises a gear 54, the motor 52 is designed such that it enables speeds of 1000 to 50000 rpm, preferably between 5000 and 30000 rpm, and a torque between 0.01 and 0.3 Nm, preferably between 0.025 and 0.25 Nm. If the seat-adjusting mechanism is constructed without gears, the motor 52 is designed such that it enables speeds between 20 and 2000 rpm, preferably between 100 and 1000 rpm, and a torque between 0.1 and 5 Nm, preferably between 0.25 and 3 Nm. In each case, the thread pitch of the spindle is in the range between 0.5 and 5 mm, and the efficiency of the spindle is greater than 50%, preferably in the region of approximately 70%.

[0043]FIG. 5 shows the seat-adjusting mechanism 50 of FIG. 4 incorporated in the seat under-frame 32. The seat-adjusting mechanism 50 comprises an actuating lever 58 which is constructed such that it is rotatable with respect to the seat under-frame 32. A lever arm 60 of the lever 58 is movably coupled to the rail 56 of the seat-adjusting mechanism 50 by way of a transverse pin 62.

[0044] To actuate the lever 58, the spindle 12 is driven by a motor (not illustrated in FIG. 5) by way of the gear 54. Since the spindle 12 is mounted such that it is stationary with respect to the seat under-frame 32, the nut 16, which is movable with respect to the seat under-frame 32, is displaced in the axial direction upon a rotary movement of the spindle 12. This axial displacement of the nut 16 is transferred to the rail 56 which is rigidly coupled to the nut 16, and also to the lever arm 60 which is connected to the rail 56, and effects adjustment of the seat. 

1. A seat having a seat-adjusting mechanism with a motor-driven spindle unit, the spindle unit comprising a) a nut which has an inner profiled portion; b) a spindle which has an outer profiled portion; and c) a plurality of rollers which are arranged in planetary manner between the nut and the spindle, each roller having at least one outer profiled portion and cooperating with both the nut and the spindle.
 2. The seat according to claim 1, wherein the rollers each have a single outer-profiled portion and, by way of this outer profiled portion, cooperate both with the inner profiled portion of the nut and with the outer profiled portion of the spindle.
 3. The seat according to claim 1, wherein the rollers each have two different outer profiled portions and cooperate with the inner profiled portion of the nut by means of a first of the two outer profiled portions, and with the outer profiled portion of the spindle by means of a second of the two outer profiled portions.
 4. The seat according to claim 3, wherein the two outer profiled portions are arranged in regions of each roller which follow one another in the axial direction.
 5. The seat according to claim 3, wherein the first outer profiled portion is coarser than the second outer profiled portion.
 6. The seat according to claim 1, wherein the outer profiled portion of each roller comprises grooves.
 7. The seat according to claim 6, wherein the grooves of rollers which are adjacent in a peripheral direction of the spindle are offset axially with respect to one another.
 8. The seat according to claim 1, wherein the nut has an inner profiled portion in the form of grooves.
 9. The seat according to claims 1, wherein the spindle has an outer profiled portion in the form of a single-lead or multi-lead thread.
 10. 10. The seat according to claim 9, wherein the pitch of the thread of the spindle is less than 5 mm.
 11. The seat according to claim 1, wherein the spindle has an outer profiled portion or the nut has an inner profiled portion in the form of a multi-lead thread, and wherein the number of rollers corresponds to the number of threads.
 12. The seat according to claim 1, wherein the efficiency of the spindle unit is greater than 50%.
 13. The seat according to claim 1, wherein the seat-adjusting mechanism is constructed without gears.
 14. The seat according to claim 1, wherein the spindle is mounted such that it is stationary with respect to a seat under-frame, and the nut is movable relative to the seat under-frame.
 15. The seat according to claim 14, wherein the seat-adjusting mechanism comprises a lever which has a lever arm coupled to the nut.
 16. The seat according to claim 1, wherein the seat-adjusting mechanism comprises a blocking mechanism for the spindle unit.
 17. The seat according to claim 1, wherein the seat-adjusting mechanism comprises a unit for determining the position or angular position of the spindle.
 18. A vehicle seat having a seat-adjusting mechanism with a motor driven spindle unit, the spindle unit having an efficiency of more than 50% and comprising a) a nut which has an inner profiled portion; b) a spindle which has an outer profiled portion; and c) a plurality of rollers which are arranged in planetary manner between the nut and the spindle, each roller having at least one outer profiled portion and cooperating with both the nut and the spindle.
 19. A seat having a seat-adjusting mechanism with a motor-driven spindle unit, the spindle unit comprising a) a nut which has an inner profiled portion; b) a spindle which has an outer profiled portion in the form of a thread having a pitch of less than 5 mm; and c) a plurality of rollers which are arranged in the manner of a planetary gear between the nut and the spindle and cooperate with the nut and the spindle, and which have each at least one outer profiled portion. 